The fermentation yield of industrial proteases has increased dramatically over the passed years. The yield is now so high that more than 60% of the protease in the fermentation broth may be present as crystals and/or precipitate.
A number of methods have been applied for solving or minimizing this problem, see e.g., U.S. Pat. No. 6,316,240, wherein the pH of the culture broth is adjusted to a pH between 9.5 and 13.0.